The present invention relates to an antireflection film and a manufacturing method thereof, and particularly to an antireflection film formed by stacking silicon oxide films and indium tin oxide films in multilevels, and a manufacturing method thereof.
In general, an antireflection film of a stacked structure having conductive films has been formed by alternately stacking, on a base film, films each having a larger refractive index and films each having a small refractive index. In many cases, the film having a small refractive index has been made from silicon dioxide (hereinafter, referred to as "SiO.sub.2 ") and the film having a larger refractive index and an electric conductivity has been made from indium tin oxide (hereinafter, referred to as "ITO"). For example, there has been known an antireflection film formed by stacking, on a resin base film, an ITO film, a SiO.sub.2 film, an ITO film, a SiO.sub.2 film, and a contamination preventive film in this order.
However, the antireflection film used to be stuck on the surface of a glass panel of a CRT (Cathode Ray Tube), for example, a Braun tube, is required to satisfy the following characteristics:
(1) The adhesive strength to a resin base film must be sufficient large. In this case, the adhesive strength is measured for the antireflection film after being left for two hours in an atmosphere in a high temperature (for example, 60.degree. C.) and a high humidity (98%) or after being repeatedly subjected to five cycles of heat history between +70.degree. C. (five hours) and -40.degree. C. (five hours). PA1 (2) The reflectance characteristic (average reflectance to light having a wavelength of 450 nm to 650 nm) must be as sufficiently small as 0.6% or less. PA1 (3) The electric resistance (to ensure electromagnetic shielding and antistatic characteristic) must be 500 .OMEGA./.quadrature. or less. PA1 (4) The transparency must be large. More specifically, the total light transmittance (to light having a wavelength of 450 nm to 650 nm) must be 90% or more.
In summary, the antireflection film used for a glass panel of a CRT is required to simultaneously satisfy the above inconsistent characteristics (1) to (4).
The above-described related art antireflection film having the stacked structure of ITO/SiO.sub.2 /ITO/SiO.sub.2 is generally difficult to simultaneously satisfy the items (1) to (4). To be more specific, the related art antireflection film allowing to satisfy them can be manufactured at the expense of the manufacturing yield, which results in the increased manufacturing cost.